BIM – When What You See is Not What You Get

Posted on 28 April, 2017 by Bogdan Pop

“The problem with BIM is that it is only as good as the data that you use. To get it right the supply chain needs to collaborate so that the manufacturer produces both accurate and the right amount of information from their BIM libraries.” This according to Bogdan Pop, Principal Public Health Engineer for Hoare Lea.

There are a number of BIM libraries that can produce designs that will not work in real life situations. So for example it’s all very well producing a 3D drawing showing a 54.3o bend in it, but you try and purchase one.

Such situations are frustrating for both the designer and also the installation contractor. This is compounded by the fact that we have a well-publicised lack of skills within the construction industry, so while in theory the diagrams can be altered on site, what can happen in practice is that the designer needs to visit to make sure the installation can be adapted.

Naturally this would be avoided if the data that we get was right first time. In fairness it is often a software problem, rather than an issue with manufacturers. Platforms will allow you to enter data and drawings, but you need to put constraints on the diagrams – so in our example above a 45o bend cannot become a 54.3o bend.

This problem is compounded if you use a generic library, where in theory anything is possible, but in practice when this reaches the project on the ground, the installation contractor will be pulling their hair out trying to conform. The only way to get BIM right is to use a manufacturer’s library and ensure that the data is right. Sadly many manufacturers have not invested the time and effort to get it right and many still rely on generic libraries.

The answer is to work with manufacturers so that they understand the needs of the supply chain. The issue of accurate data may seem obvious, but unless you know that the data can be and needs to be constrained it does not become a problem until a system is designed and by then it is too late.

Another example is in thinking through how much data is actually needed through BIM. The temptation is to provide as much detail about the products as possible, which may seem sensible, but it does lead to problems.

A 3D drawing that contains too much information can take too long to download and actually place in a design. Bearing in mind that a single product, let’s say a push fit branch tee for an above ground drainage system, is only one component of what could be an extensive system

A lot of detail is often un-necessary, we have had examples from manufacturers that have included the threads on a joint. It just slows up the design process. The trick is to provide just enough data.

In fairness it is impossible for a manufacturer to know how much data is required from a 3D drawing and it is a judgement that can only be reached by working together.

The great thing is that the construction industry is moving forwards and we are genuinely seeing collaboration on projects that benefit all. BIM in a number of ways is the ultimate manifestation of this new era helping to ensure that what was intended from the outset is delivered on site.

The initial data has to come from the manufacturer, generic libraries are of no use to anyone, but equally the manufacturer has to work closely with the organisations that will use the information.

By providing feedback and working together as an industry we can overcome what are just teething problems and make BIM a tool that works hard for everyone in the supply chain.

Hoare Lea is an international firm of mechanical, electrical and public health (MEP) consulting engineers.